1. Field of the Invention
The present invention relates to a rubber-laminated metallic plate, and more particularly to a rubber-laminated metallic plate having a good resistance to an antifreezing fluid and a good utility in gasket materials, etc.
2. Description of the Prior Art
JP-A-2-29484 discloses a process for producing a gasket material by forming a primer layer composed mainly of phenol resin on one side or both sides of a metallic plate and then forming a vulcanized rubber layer from a rubber solution comprising carboxyl group-containing NBR having a carboxy monomer content of 2 to 15% by weight, zinc peroxide and sulfur or a vulcanization accelerator thereon.
It is disclosed that the thus obtained gasker material has better rubber strength and bonding strength of the rubber layer to the primer layer without any occurrence of cracking or blister in the region exposed even to severe impact and friction conditions, and also has good heat resistance and scorch retardability because of use of the sulfer-zinc peroxide vulcanization system.
However, the gasket made from these materials still has such a problem as swelling of rubber and the resulting blister due to contact with an antifreezing fluid to cooling water, when applied as a gasker for engine heads, which are important gasket application sites. Particularly, when the gasket is half dipped in an antifreezing fluid at a higher temperature than 130.degree. C., blisters occur in regions in contact with the fluid and its vapor within a short time such as about 70 to 500 hours, resulting in peeling of the rubber layer and the primer layer.